[8o 



MILK 



A sample of milk is thoroughly mixed (see p. 176) 

 and is poured into a gas jar or other vessel of suifficient 

 diameter to allow at least a \ inch clearance between 



Fig. 23.— Westphal balance. 



the float and the sides of the vessel, in order to avoid 

 the effects of surface tension. The level of the surface 

 of the milk should be sufficiently high to allow of a 

 complete immersion of the float. The riders are then 



